Studies on fat digestibility: The effect of melting point and dietary calcium and magnesium level

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Content STUDIES QN PAT DIGESTIBILITY; THE EFFECT OF MELTING POINT AND DIETARY CALCIUM AND MAGNESIUM LEVEL A Dissertation Presented to the Faculty of the Graduate School University of Southern California In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy by Amber Lieng-shah Cheng UMI Number: DP21537 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI DP21537 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346 810, This dissertation, written by ....... A M E R ..M E N (H S M N .M E N G ........... under the guidance of H3.1P... Faculty Committee on Studies, and approved by all its members, has been presented to and accepted by the Council on Graduate Study and Research, in partial fu l fillment of requirements for the degree of DOCTOR OF P H IL O S O P H Y Committee on Studies TABLE OF CONTENTS CHAPTER PAGE I, INTRODUCTION............ 1 II. HISTORICAL REVIEW ................ 3 III. GENERAL PROCEDURE . . . ... , . 13 Plan of experiment............... 13 Diet used .............. 13 Preparation of fats ................. 1? Blending of fats to obtain fats with inter mediate melting points ........... 1? Synthetic calcium soaps 1? Physical constants on fats ^ 18 Melting point . . ....... ......... 18 Free fatty aeid ......... 19 -Iodine number ........... ....... 20 Saponification number ............ 20 Acetyl number 20 Fecal analysis ... ......... 21 Correction for metabolic fat .......... 21 Calculation of Digestibility .......... 22 Method of calculation of statistical significance 22 IV. EXPERIMENTAL RESULTS AND DISCUSSION .;..... 25 V, SUMMARY AND -CONCLUSIONS ....... 42 Summary ......... .............. 42 Conclusions ........ . .............. 43 BIBLIOGRAPHY . . * . . i ........................ 45 APPENDIX 48 LIST OF TABLES TABLE PAGE 1, Composition of Diets . ....................... 14 XI* Composition of Diets used when Calcium Soaps were fed .......... 15 III. The Composition and physical Constants of the Materials used in the Digestibility Coefficient Studies .......... 22 IV. The Determination of Metabolic Fat in Rats on Diets Containing Calcium and .Magnesium Salts....... 23 V. The Determination of Metabolic Fat in Rats on Diets Containing no Calcium and Magnesium Salts .... 24 VI. Summary Table of Digestibility of Natural Fats . . 26 VII. Summary of Digestibility of Hydrogenated Natural Fats 2? VIII. Summary Table of Digestibility of Two Liquid Oils . 28 IX. Summary Table of Digestibility of Trilaurin .... 29 X. Summary Tables of Digestibility of Triglycerides and MOnoglyceride . ......... ........ 30 XI. Summary Tabie of Digestibility of Two Calcium Soaps and their Fatty Acids ..................... 31 XII. Physical Constants on Rapeseed Oils ....... 35 XIII. Summary Table of Physical Constants on Fat Excreted after feeding Triglyceride................. 41 CHAPTER I IMKOIXJCTION . Fats op oils as they exist in nature are the esters of fatty acids and the tri-hydroxy alcohol,glycerol. In evaluating the importance of natural fats or oils for edible purposes, di gestibility is of fundamental importance. In general, tnis con sists of a breakdown of the fat molecules by the digestive en- zjnnes to smaller, more soluble substances. The absorption of these products by the membranes of the digestive tract must occur before they can be used by the organism for fuel or to form characteristic fatty substances of the body. Previous work has thrown some light on enzyme action and the processes concerned in the absorption of the split products. In recent years, considerable work has indicated some of'the interrelationships of the physical-chemical properties of fats and oils and the effects of these upon digestion. Melting point as influenced by the chain length and the degree of satu ration of the constituent fatty acids has received considerable attention. The present study is designed to correlate the effect of the divalent ions, calcium and magnesium, with the effect of the melting point upon digestibility. A number of natural and synthetic fats of various melting points has been studied with the hope of obtaining evidence which may explain in more detail the differences noted in digestibility. CHAPTER II HISTORICAL REVIEW .Tie first worker to make progress in the study of lipases was Bernard in 1856 (6), who found that pancreatic juice both emulsified and hydrolyzed fats and oils, Sandmeyer (46) showed that when finely minced pancreas was fed to pancreatectomized dogs, fat absorption was greatly improved, Jansen (31) noted that the implantation of pancreas under the skin results in satisfactory absorption, although the reason for this result is not apparent, Exclusion of pancreatic juice from the in testines by pancreatectomy results in serious disturbance of fat absorption as shown by Pratt, Lsmson, and Marks (42) and McClure, Vincent, and Pratt (39). Coffey, Mann and Bollman (11) studied the fecal excretion of fat in normal and pancreatectomized dogs, and animals in which the pancreatic juice had been excluded from the intestine by ligation of the pancreatic ducts or by external pancreatic fistula. In the normal animal, only three to four per cent of the ingested fat was recovered in the feces, whereas in the preparations where pancreatic juice was excluded from the intestine, from 54 to 76 per cent of the fat fed was not absorbed. The existence of fat-splitting enzymes in the gastric juice and intestinal juice itself has also been demonstrated. Willstatter, Waldschmidt, and Memmen (51) showed the presence of a gastric lipase 4. of much lesser activity than that derived from the pancreas. Much earlier Schiff (47) found a considerable splitting of fat by depancreatized animals and attributed it to the activity of intestinal juice. Boldyreff (8) collected secretions from a Thiery-yella fistula and found that it rather fully hydrolyzed neutral fats. Kalabeukoff and Terroine (32) reported that a glycerol extract of intestinal mucosa was lipolytic. Mellanby (37) showed that the vagal control of secretion of a pancreatic juice of high enzyme content may play the dominant role in pan creatic digestion, whereas the production by seeretin of a copious flow of a dilute bicarbonate solution containing only small amounts of pancreatic enzymes may not be essential to normal digestion. The importance of this alkaline fluid is to secure an optimal medium for the activity of lipase and other enzymes. Harper and Raper (23) have described another hormone, pancreozymin, which stimulates the production of amylase and trypsinogen but has no effect on the volume of juice secreted. Confirmatory evidence has been secured by Greengard, Grossman, and Ivy (22) for the existence of pancreozymin which stimulates equally the formation of three chief pancreatic enzymes, namely, amylase, trypsinogen, and lipase. It is generally believed by verzar and Mepougall (49) and Bloor (7) that the triglycerides must be completely hydrolyzed by pancreatic lipase to fatty acids and glycerol before they can be absorbed from the intestinal lumen. These workers suggest that the absorption of the unhydrolyzed triglyceride is impossible. On the other hand, Frazer (19.) supports the theory that complete breakdown of the fatty acid molecule is not necessary for absorption* He postulates that absorption of at least a part of the fat is due to a finely divided emulsion. Mono- and di-glycerides together with bile acids are the substances active in producing emulsifi- cation. Thus, in the form of these finely divided emulsions, unsplit fat particles of 0.5^ or less may enter the absorbing mucosa. According to either theory, lipase is essential in the preparation of the fat molecule for absorption. For more than fifty years, it has been recognized that the degree of enzyme activity and the absorption of these products is in some way related to the melting point. Arnschrink (1), working with dogs, found tristearin with a melting point of 6Q°C to have an absorption of 9 per cent, while olive oil, melting at 0°C, was absorbed up to 90 per cent. Frank (18) recorded the absorption of ethyl stearate by dogs as 12.7 per cent and ethyl palmitate as 86.3 per cent. Levites (36) compared the absorption of palmitic and stearic acids along with their sodium soaps. The palmitic acid was absorbed to the extent of 63 per cent, whereas the ab sorption of stearic acid was only 19.0 per cent. In the form of soaps, digestibility was greater. In studies of natural fats of low melting point, Smith, Miller and Hawk (48) observed that lard (m.p. 45°G) and hydrogenated cottonseed oil (m.p. 36°C) were approximately 95 per cent digested. Because of the relation of fats to agriculture and their importance in the diet, a series of experiments were conducted by Langworthy and Holmes (34, 35), Holmes (26, 27, 28), Lang worthy (33), and Deuel and Holmes (16, 29) in the Office of Home Economies in Washington to determine the coefficient of digestibility of a number of fats and oils which are consumed in j&merica. . The results seemed to indicate that the coefficient of digestibility of fats having a melting point above 50°C varies inversely with the melting point. They reported that most of the common oils of animal and plant origin are from 93 to 98 per cent utilized by the human body. However, there are exceptions. Mut ton fat, oleo-stearin, deer fat, and some of the hydrogenated fats having melting points between 50°C and 6Q°C gave values as low as 79 per cent average coefficient of digestibility. Rock- wood and Sivickes (44) independently found that corn oil and cottonseed oil were well digested. More recently, as a result of the war situation, the question of fat supply and fat utili zation has resulted in considerable attention being focused on this problem. Certain fats, notably butter, natural vegetable oils, and their derivatives, as well as margarine, have assumed especial prominence in this connection. Rapp, Skinner and McHargue (43) fed tobacco-seed oil to rats at levels of 5* 15, and 30 per cent of the respective rations and showed an average coefficient of digestibility of 97.9 per cent. Basu and Hath (5) worked on mustard, coconut, sesame, and hydrogenated peanut oils, as well as cow and buffalo butter fats which are used widely in India, All of these fats were digested to the extent of 94-99 per cent except the hydrogenated peanut oil, which had a coefficient of digestibility of only 89.0 per cent. Crockett and Deuel (13) studied the coefficient of digestibility of various fats including margarine, Crisco, prime steam lard, bland lard, and hydrogenated lards. Augur, Bollman, and Deuel (3) studied the utilization of cottonseed oil hydrogenated to various melting points, while Deuel (15) studied the digestibility of margarine on human subjects. All the fats and oils studied were equally well digested, except the hydrogenated lards (m.p. 49°C) and (m.p. 6l°C) and cottonseed oil (m.p. 45°C, 54°C, and 65°e) which have digestibility coefficients of 63, 21, 83.8, 68.7, and 24 per cent respectively. These are considerably lower than the minimum value of 79 obtained in the experiments carried out by the Department of Agriculture of the United States on human sub jects using fats melting between 50°G and 54°C. However, the method of extraction of fecal fat by those workers was such that only such extractable substances as fatty acids and neutral fats were de termined. It is possible that these results may be incorrect because variations in excretion of the unextracted soaps might obtain. In the later work on rats (13, 3), account was taken of 8. the fraction excreted as soap. Lyman (37) suggested that the nature of the fatty acid radical of an ester has an effect on digestibility other than its effect on the melting point of the compound. He observed that esters of palmitic acid and stearic acid do not differ markedly in their melting points, the ethyl esters of both being liquids and the gljrcerol esters being solids at body temperature. However, there is a wide difference as to diges tibility. Gox (12), working with white rats, found that ethyl laurate was better ana more completely absorbed than ethyl stearate or ethyl palmitate. Holt, Tidwell, Kirk, Gross, and Neale (30), in studies on infants, using a partially hydrogenated corn oil (m.p. 50°C, I no. 2.4) found 83 and 61 per cent absor ption. These two fats have practically the same melting points, but differ widely in their content of unsaturated fatty acids. He suggested that the presence of unsaturated fatty acids insures good absorption regardless of the presence of any fatty acids or high melting points. Hoagland and snider (24) noted that mutton tallow (m.p.- 47°C) had a considerably higher digestibility than Cacao butter (m.p. 28°C). The relatively low melting point of Cacao butter is due to the even distribution of unsaturated fatty acids in the molecules, whereas mutton tallow contains a consider able proportion of fully saturated fatty acids, chiefly stearic and palmitic acids. \ It has also been suggested that some of the discrepancies between digestibility and melting point may be traced to a species difference. Gogi|#®tse (21) noted that the high melting fats were absorbed with difficulty in goats. The conclusions of Lyman (37) that palmitic acid was much better absorbed than stearic acid was based upon experiments on dogs. McCay and Paul (38, 41) fed cottonseed oil and hydrogenated fat to guinea pigs and rats. Their results indicated that the higher melting fats are not as well utilized in guinea pigs as in rats. Moreover, the rat is able to utilize castor oil. In later tests, it was round that both rabbits and sheep digested hydrogenated fats as well as liquid fats, while the rabbit was also found to utilize cas tor oil. In view of the rather wide differences of the coefficient of digestibility of certain fats when based purely upon melting point, correlation in digestibility of several pure saturated fatty acids and their corresponding triglycerides was' studied by Hoagland and Snider (25). They obtained values of 6 to 9 per cent for the coefficient of digestibility of 'stearic acid. The digestibility of tripaimitin (m.p. 65.1°C) was 84 per cent. Tri- myristin (m.p. 56.5°C) and trilaurin (m.p. 46.4°0) were found to be almost completely digestible. It has been suggested that the decrease in utilization of the higher melting fats is due to the increasing proportion of tristearin in these fats. Erom 10* the work of Mattil and Higgins (36), it has been shown that mixed triglycerides are more readily digested than simple tri glycerides. He explains this by postulating a ’ ♦solvent** action of oleic acid for stearic acid. Thus the greater solubility of the mixed triglycerides as compared to that of tristearin would result in an increased rate of hydrolysis. Studies attempting to correlate calcium absorption with the fat content of the diet have been reported. Cronheim and Muller (14) and Bahrdt (4) in studies on children, noted that there was an increase in the soap content of the stools when the amount of fat in the diet was increased above a moderate level. Eothberg (45) showed that a negative calcium and mag nesium balance obtained on a high fat diet. Givens (20), studying the absorption of lard, ethyl palmitate, and palmitic acid, demonstrated that when the utilization of fat or fatty acids was poor, the excretion of calcium increased. Storage Of calcium was decreased even when the intake was at a high level, Bosworth, Bowditch and Giblin (9) concluded that the presence of ionized calcium in the intestine determines the extent of soap formation, although the excretion depends upon the nature of the salt formed and its solubility. Boyd* Crum, and Lyman (10) compared the calcium and fatty aeid content of the feces of rats which had been fed the calcium salts of oleic, palmitic and stearic acids. When the calcium intake was rela 11. tively high, between 60 and 70 mg. per day per rat, the soap utilization was found to be 90, 38, and 25 per cent for the oleate, palmitate, and stearate respectively. When the soaps were fed at a lower level, with the calcium intake lowered to 13.6 to 31.4 mg,."' per rat per day, the percentage absorption in the palmitate and stearate increased to 65 and 45 respectively. Since some of the confusion existing as to the factors affecting digestibility of fats may be due to incomplete data on the soap excretion, studies were designed to clarify this point. It was felt that differences due to a change in melting point might be even greater than the early work indicated, since inclusion of the soap fraction in the total could decrease the digestibility figures to a greater or lesser extent. Thus, studies of the amount of fat excreted in the neutral fat and fatty acid fraction as compared with that excreted as soap were made both upon well and poorly absorbed fats. Comparison of digestibility of synthetic glycerides and the fatty acids con cerned were also carried out in hope of shedding light on the importance of individual fatty acids on digestibility. Further studies on the effect of the divalent ions calcium and magnesium on digestion were also made. Because of the greater insolubility of the calcium and magnesium soaps over the sodium and potassium or the free fatty acids, it was felt that any decrease in digesti bility might be tied up with an increase in excretion of these insoluble soaps. Further evidence for this would be gained by noting the effects of the soaps when fed preformed and by vari ations in the amount of the divalent ions in the diet. CHAPTER III GENERAL PR0CEX3UKE 1. Plan of Experiment Adult female rats weighing between 145 and 300 grams were placed in single cages having false bottoms so that fecal matter could be quantitatively collected. The food containing the fat to be tested was placed in a eup and the animal allowed to eat ad libitum. A two-day orientation period was allowed. In the following period, the amount of food consumed was noted, as well as the change in weight of the animal. In most cases, the inter val was of eight days* duration, although in a few instances a shortage of the fat required that the period be reduced b? two or three days. At the end of this period, the pooled feces of each animal were dried and analyzed for their content of neutral fat, fatty acid, and soap. Corrections for metabolic fat were made by similar experiments where the food fed contained no fat. 2. Biet used The percentage composition of the diets is shown in Tables I and II. In general, fat was fed at a 15 per cent level in each experimental diet. In the case of the studies on the digestibility of the calcium soaps (such as diets E and F) the sum of the free fatty acid and that in the soap very closely approximated the 15 per cent level. In this case the amount of calcium combined with TABLE I COMPOSITION OP DIETS Control Experimental Diet Diet Diet Diet Diet Diet I II A B C D Commercial casein 18 18 18 18 18 18 Fats or oils - - 15 15 15 IS Osborne-Mendel salt mixture 7 - 7 - - - Modified salt mixture2 - 5 - 5 - - 3 Modified salt mixture - - - mm 5 - Modified salt mixture^ - - - - S Yeast - Anheuser-Busch, Ind, Strain G. 1 1 1 1 1 1 Glucose - commercial cerelose 74 76 59 61 61 61 1. Osborne-Mendel salt mixture (40). 2. Same salts, except that those containing either Calcium or magnesium were excluded. 3. Same salts as No. 1, except that the calcium and , magnesium salt was reduced to l/2. 4. Same salts as No. 1, except that the calcium and magnesium salt was reduced to l/4. TABLE II COMPOSITION OF DIETS USED WHEN CALCIUM SOAPS WERE FED Components of Diet Experimental Diet DietT 1 F Commercial casein 18,00 18.00 Soap: Calcium stearate Stearic acid Total stearic acid 10,47 5,21 14*94 Calcium palmitate Palmitic acid Total palmitic acid 10.00 5,68 14,94 * Modified salt mixture 5,00 S. 00 Yeast - Anheuser-Busch, Inc. Strain G 1,00 1,00 Glucose - commercial eerelose 60,00 60.00 * The composition of the salt mixture was the same as Osborne-Mendel salt mixture, except that calcium and magnesium were eliminated. 16. the fatty acid was equivalent to the amount of calcium that would have been present if the usual amount of normal salt mixture had been added to the diet. Diets I and II contained no fat and differed only in that the first contained the normal Osborne-Mendel salt mixture, while the latter had the modified mixture which contained no calcium or magnesium. In each case, diet A refers to that containing the salt mixture which supplies calcium and magnesium, while diet B refers to that containing no calcium or magnesium. Diets C and D were employed only in the study of the diges tibility of the synthetic fat, trilaurin. In diet 0, the content of divalent ions equals one-half that of diet A, while the content of divalent ions in D is one-quarter that of A. The fats and oils studied were divided into four groups: (1) Natural fats and oils (a) Bland lard (m.p. 47.8°C) (b) Hydrogenated lard (m.p. 55.4°G) (c) Hydrogenated lard (m.p. 61°C) (2) Mixed natural fats (a) Mixed - fat A (m.p. 47.9°C) This fat is a mixture of 1/10 hydrogenated lard (m.p. 61°C) and 9/10 of prime steam lard (m.p. 36,7°G) (b) Mixed - fat B (m.p. 55.2°0) This fat is a mixture of 1/3 hydrogenated lard (m.p. 61°c) and 2/3 prime steam lard (m.p. 36.7°0) 17. (3) Synthetic fatty acids and simple glycerides (a) Palmitic acid (m.p. S3.0°C) (b) Stearic acid (m,p. 69.0°G) (c) Monostearin (m.p. 59,9°C) (d) Trilaurin (m.p. 49°C) (e) Trimyristin (m.p. 56.0°C) (f) Tripalmitin (m.p. 66,5°C) (g) Tristearin (m.p. 70.0°C) (4) Synthetic calcium soaps (a) Calcium palmitate (b) Calcium stearate 5.Preparation of fats Blending of fats to obtain fats with intermediate melting points. Definite amounts of the two fat components were weighed in separate containers and melted. The two melted fats were mixed thoroughly by a stirrer. After the mixed fats were cold, the melting point was determined. Synthetic calcium soaps. The soap was prepared by the following steps, as described by Smith and Ross (49): a. Potassium soap - A weighed amount of fatty acid was placed in an Erlenmeyer flask and heated until melted. The melted fatty acid was neutralized with 0.5N alcoholic potassium hydroxide, using phenolphthalein as an indicator. Vigorous shaking after each addition of alkali insured a complete reaction. The potassium 18* soap formed, was filtered off and freed from alcohol by washing with acetone. The soap was then dried to constant weight over phosphorus pentoxide. b. Calcium soap - A calculated excess of CaCl- was dis- solved in a large volume of water. The potassium soap, dissolved in a minimal quantity of water, was poured slowly into the CaC^ solution. Both solutions had been warmed to 60°C. During the addition of the soap solution, the precipitation mixture was vigorously stirred. The calcium soap was separated by filtration on a Buchner filter, and washed with distilled water until the addition of silver nitrate solution to the filtrate produced no turbidity. The soap was then dispersed in acetone and filtered. The precipitate was washed with acetone until any remaining fatty acid or water was removed. The soap was dried in air until light and powdery. Then it was dried to constant weight in the oven at U0°C. 4. Physical Constants on fats Melting point - Melting points of all natural and mixed hydrogenated fats were determined by the Wiley method (2). An aluminum plate containing several circular openings of 1.0 cm, diameter was placed on a copper sheet ehilled by ice. A quantity of melted fat sufficient to fill each hole was dropped upon the sheet. The fat was allowed to solidify. The discs were covered 19, and placed in tne refrigerator for at least 30 minutes, in order to assure uniform consistency and a normal melting point. A 30x3.5 cm. test tube, containing tne alcohol-water mixture, is placed in a tall 39x10 cm. beaker containing ice and water, and left until the mixture is cold. The fat is dropped directly into the tube. The ,fat : will sink immediately to a point where the density of the alcohol-water mixture is exactly equivalent to its own. The thermometer is lowered into the test tube until the bulb is just above the fat disk. Then the water in the beaker is heated, with constant stirring by means of a stream of airi When the disk of fat begins to shrivel and gradually rolls up into an irregular mass, the thermometer is lowered until the fat particle is even with the center of the bulb. The thermometer bulb is rotated gently and the heat so regulated that 10 minutes are required for the last 2° increase in temperature. As soon as the fat mass becomes spherical, it is considered to have melted, and this temperature is taken as the melting point. The melting points of the synthetic fatty acids and tri glycerides were determined by the capillary tube method (2). The fat powder is introduced into a thin-walled capillary tube and one end of the tube is sealed. A column of fat 1-2 cm. long is used, according to the length of the thermometer bulb. The capillary tube is attached to°the bulb of a thermometer accurately graduated to 0.2°C. It is then immersed in a large test tube of 20. water surrounded by a beaker of water, which is heated very slowly. The melting point is taken to be the temperature at which the substance becomes transparent. Free fatty acid - In this study, the free fatty acid was determined on extracted fats only. The method was described by Woodman (53). The fat was dissolved in 95$ alcohol and heated on the water bath nearly to boiling. The solution was then titrated with 0.1N alkali and phenolphthalein until the pink color persists for at least one minute. The result was expressed as the milligrams of potassium hydroxide required to neutralize the free fatty acids in one gram of oil or fat. Iodine number - The iodine number of natural fats and — . \ mixed natural fats was determined on the fat before absorption. In the case of rapeseed oils, the iodine number of the oil fed and that not absorbed was determined. The Wijs method was used for this determination (53), Saponification number - The procedures are outlined by Woodman (53). The saponification number was determined on the original fats. In the case of the rapeseed oils, the saponification number of unabsorbed fat was determined in addition to that of the oil fed. Acetyl number - The acetyl number was determined according to West, Hoagland, and Qurtis (51), The fats were allowed to react with a mixture of acetic anhydride and pyridine. On the addition 21. of water, the excess acetie anhydride forms aeetic acid. This is titrated with 0.3 to 0.35 N alcoholic KOH. A blank deter mination is run; at the same time. The acetic anhydride used for the acetylation of the fat can then be calculated from the titration difference. The acetyl number is obtained from this value. The physical constants of the fats and oils are in Table III. 5 , Fecal analysis - At the end of a given eifeht“day collection period, the pooled feces of each animal were dried in vacuo until constant weight had been obtained. The dried material was pulverized and extracted with diethyl ether. After 6 hours of extraction, the ether was removed by evaporation. The last trace of ether was removed in the vacuum. This first ether extraction was recorded as neutral^and fatty acid. The fecal residue Was again dried, mixed with a minimum amount of 50 per cent sulfuric acid to form a paste, and the paste was extracted again with ether. The ether was removed from this second extraction by evaporation and the flask was dried in the vacuum. The second extraction isolated the soap as free fatty acid. 6. Correction for Metabolic Fat Besides the undigested fat from the diet, there is present in the stool another type of fat, metabolic fat. This metabolic fat TABLE III THE COMPOSITION AND PHYSICAL CONSTANTS OF THE MATERIALS USED IN THE DIGESTIBILITY COEFFICIENT STUDIES Supplement fed Source Physical Constants Melting Saponification Iodine Acetyl point number number number °c. Bland lard Swift and Company 47*8 70.0 Mixed-fat-A Prepared 47,9 76,0 Hydrogenated Lard Swift and Company 55.4 33,4 Mixed-fat-B Prepared 55.2 45,2 Hydrogenated lard Swift and Company 61,0 . * 1.6 Crude Rapeseed oil Pacific vegetable Oil, Liquid 101.6 166,8 San Francisco Refined Rapeseed Pacific Vegetable Oil, Liquid 96,3 167,7 oil San Francisco Monostearin Best Foods, Inc, 59,9 156.7 144,0 Trilaurin Eastman Kodak Go. 49,0 Trimyristin t t t r t t 56,0 Tripalmitin f t t t I I 66.5 Tristearin f t t t f t 70.0 Palmitic acid f t t t t t 63.0 Stearic acid t t t t t t 69.0 Calcium palmitate Synthesized Calcium stearate Synthesized 2SA is derived from the intestinal wall, possibly formed from fats and fatty acids present in the blood stream. To obtain this correction, one group of ten animals was fed a fat-free diet containing calcium and magnesium salt, and a similar group was fed a diet lacking not only fat but also calcium and magnesium. The 15 per cent of fat was replaced by glucose* The extraction procedures were the same as previously described. Calculations for the amount of metabolic fat per gram of feces were made. These data are recorded in TablesIY and V. 7. Calculation of Digestibility The amount of ingested fat can be obtained from the weight of food ingested. The fecal fat is corrected by applying the correction for metabolic fat. Prom the converted figure of total fat excreted, the fat digested and absorbed is obtained by sub tracting from the ingested fat this corrected value for excreted fat. The coefficient of digestibility is the amount of fat di gested divided by the amount of fat ingested. 8. Method of Calculation of Statlstiqal Significance * The standard error of the mean was determined for each experiment. The deviation of each animal from the group average was squared and the sum of the squares determined. Standard error of the mean f sum of the squares number of rats f number of rats TABLE IV THE DETERMINATION OF METABOLIC FAT IN RATS ON DIETS CONTAINING CALCIUM AND MAGNESIUM SALTS Rat No. Body weight Food eaten (gnu) Dry Weight of Feces (gnu) Extracted fat in feees Fat per gram of feces (gnu) Start (gm.) End (gnu) Neutral Fat and fatty acid (gnu) Soap (gn.) Total (gn.) 40*L 180 166 60 3,063 0.146 0,116 0.262 0,085 402 161 160 68 3,728 0.120 0.113 0.233 0,063 403 164 152 63 4.353 0.214 0.144 0,358 0.082 404 147 139 31 2.230 0,165 0.078 0.242 0.108 405 166 155 71 4.236 0.136 0.176 0.312 0.074 806 186 191 89 5.154 0.085 0.167 0*252 0.084 807 153 161 89' r? 4.027 0.075 0,099 0.174 0,043 808 188 180 60 4.201 0.099 0.150 0,249 0.059 809 168 168 70 3,332 0.072 0,092 0.164 0.049 900 190 188 87 4.182 0.074 0,090 0.164 0.039 Averagel7©,3 166 68,8 3,827 0.125 0,123 0.241 0.065 TABLE V THE DETERMINATION OF METABOLIC FAT IN RATS ON DIETS CONTAINING NO CALCIUM AND MAGNESIUM SALTS Body weight Extracted fat in feces Fat per Rat no. Start (gnu) End Food (gm,) eaten {m») Dry weight of feces (gnu) Neutral fat and fatty acid (gnu) Soap (gnu) Total (gnu) gram of feces (gnu) 701 163 162 86 1.089 0.109 0,070 0.178 0.163 702 159 156 66 1,301 0.163 0,007 0.170 0.130 703 162 153 93 2,782 0.218 0,081 0,299 0.107 704 162 157 71 1,253 0,116 0,055 0.171 0,137 705 163 168 89 1,681 0,193 0.065 0.258 0.153 901 161 161 87 1,841 0.185 0.143 0.328 0.177 902 178 178 74 1,257 0.132 0.090 0.233 0.185 903 17© • 170 37 1,309 0,114 0.053 0,166 0.126 904 161 161 73 1,403 0,169 0,086 0.255 0.181 905 178 178 81 1,344 0,095 0.066 0,162 0.121 Averagel65.7 164,4 75.7 1,526 0,149 0.072 0,222 0.148 CHAPTER IV EXPERIMENTAL RESULTS AND DISCUSSION The results of digestibility are shown in Tables VI to XJ. When diets containing the usual amounts of Osborne-Mendel salt mixture were fed, the data show clearly, that natural fats such as bland lard and mixed-fat-A with a melting point below 50°C have an average digestibility of 95 per cent. However, when the synthetic fat trilaurin, with a comparable melting point (49°C), was fed, only 70,5 per cent was found to be digested. Since the blended fats were a mixture of a high melting fat and low melting point fat, it would seem that a high melting fat in a blend will not impair digestibility as long as the melting point of the blend remains below the critical value of S0°C. When, however, the melting point of the fat is raised above the critical 50°C, a decrease in digestibility is apparent. Thus, the lard hydro genated to sueh an extent that the melting point was 55,4°C had a digestibility of only 58 per cent, A produet made from blending the completely hydrogenated fat and the prime steam lard in such proportion that its melting point was approximately the same (55,2°C) showed a similar decrease, with a digestibility of 66.2 per cent. In the synthetic glycerides where there can be no efrect due to a mixture of fatty acids, the decrease of digestibility with increase in melting point is even more striking. Thus, trimyristin TABLE VI SUMMARY TABLE OF DIGESTIBILITY OF NATURAL FATS ' Bland lari Mixed-fat-A^ (m.p. 47.8°C) (m.p. 47.9 C) Data Summarized Diet A Diet B Diet A Diet B Number of rats § 5 5 5 Average gain, gm. 2 2 3 3 Average fat ingested, gm. 13.29 12.21 14.09 12,51 Average weight of 5.74 2.73 6.2® 2,38 stools, gm, Average fat excreted as: Neutral fat and fatty 0.25 0.39 0.24 0.38 acid, gm. Soap, gm. 1.16 0.54 1,43 0.57 Average metabolic fat,gm. 0.35 0.43 0.40 0.35 Average fat excreted, 1.03 0.51 1,27 0.61 (corrected), gm. Coefficient of . Digestibility 92.4^0.94 95.8± 0.6 90. 7 ±2. 2 95,6*£o.51 1. Including standard error of the mean. 2, A mixture of 1/10 hydrogenated lard (m.p. 6l°C) and 9/10 prime steam lard (m.p, 36.7°c) TABLE ¥11 SUMMARY OF DIGESTIBILITY OF HYDROGENATED NATURAL FATS Data summarized Hydrogenated Lard (m.p. 55.4°G) Mixed-fat~B2 • tm.p. 55.2°C) Hydrogenated lard (m.p. 61°C) Diet A Diet b Diet A Diet B Diet A Diet B NUmher or rats 5 5 5 5 3 5 Average gain, gm. 0 3 -1 *1 -1 Average fat ingested, gm. 11.77 9,13 10.68 9.06 10.93 10.56 Average weight of stools, gm. 8.00 3.78 6.90 3.60 12.05 9.92 Average fat excreted as: Neutral fat and fatty acid, gm. 0.51 1.17 1.06 1.33 8.78 5.98 as "soap”, gm. 4.67 1,40 2.9? 1,16 6,03 1.99 Average metabolic fat, gm. 0.52 0.56 0.45 0.53 0.78 1.47 Average fat excreted, corrected, gm. 4.66 2.01 3.57 1.75 9,03 6.50 Goeffieient of digestibility** 58. 012. 4 77,9±4,8 66.2±1.8 80.Oil.9 17.343.Ci 38.0± 1. Including standard error of the mean. 2. A mixture of 1/3 hydrogenated lard ,(m.p. 61°G) and 2/3 prime steam lard (m.p. 36.7°G) TABLE VIII SUMMARY TABLE OF DIGESTIBILITY OF TWO LIQUID OILS Data summarized Crude rapeseed oil (liquid at rm. temp.) Refined rapeseed oil (liquid^at rm. temp.) Diet A* Diet B Diet A1 0 Diet B Number of rats 10 5 10 5 Average gain, gm. 4 -5 -1 7 Average fat ingested, gm. 12.1 10.41 7.8 10.80 Average weight of stools, gm. 6.47 2.90 5.43 1,92 Average fat excreted as: Neutral fat and fatty acid, gm. 1.07 0,66 0.65 0.57 Soap, gm. 2.12 0.51 0.99 0.39 Average metabolic fat, gm. 0.42 0.37 0.22 0.29 Average fat excreted, 2,77 0,80 1,42 0.66 (corrected), gm. _ 93.9 + 0,62 Coefficient of digestibility 77+1,6 92.3 + 1.4 82 ±1.5 !♦ Including standard error of the mean. 2. Diet A takem from (17). TABLE IX SUMMARY TABLE OF DIGESTIBILITY OF TRILAURIN Data summarized ' . . ' ’ 1 1 • ■ 1 Diet A Trilaurin (m.p. Diet B , 49°C) Diet 0 . * , . | . < Diet D Number of rats 5 5 5 5 Average gain, gm. * • 5 2 7 -5 Average fat ingested, gm. 8.85 8.75 7.56 9.96 Average weight of stools, gm. 4.80 1. 55 1.98 2.47 Average fat excreted as: Neutral fat and fatty acid, gm. 0.25 0.16 0.23 0.38 '•Soap", gm. 2.72 0.29 0.85 0,79 Average metabolic fat, gm. 0.S1 0.23 0.13 0.16 Average fat excreted, (corrected),gm. 2.61 0.22 0,94 1.01 Qoefficient of digestibility1 70.5A1.,7 97.313.7 87.214.0 89.510.85 1. Including standard error of the mean. TABLE X SUMMARY TABLES OF DIGESTIBILITY OF TRIGLYCERIDES AMD MONOGLYCERIDE Data summarized Trimyristin (m.t). 56°C) __ Tripalmitin {m.n.. _.6_6.5°C)_ Tristearin (m.t>. 70°C) Monostearin (m.o. 59.9°C) . Diet A Diet B Diet A Diet B Diet A Diet B Diet a Diet B Number of rats 5 5 5 5 5 5 5 5 Average gain, gnu 5 3 -2 -1 0 -2 •10 •5 Average fat ingested, gm. 12.75 9.69 9.09 9,81 9.54 9.00 10,14 9.48 Average weight of stools, gm. 10.55 4.43 11.67 10.37 12.11 10.56 12.10 7.37 Average fat excreted as: Neutral fat and fatty acid, 1.12 1.49 6.40 7.51 7.50 7.97 3.22 4.00 gm. "soap'*, gm. 7.46 1.33 2.27 1.27 1,90 0.88 5,55 1.84 Average metabolic fat, gm. 0,68 0.56 0.76 1.54 0.79 1.55 0.72 1.09 Average fat excreted, (corrected), gm. 7.90 2.26 7.92 7.25 8.61 7.28 8.06 4.75 Coefficient of Digestibility^ 37.7*1,4- 76.6*8,1 12.8*1.,2 27.9*1.5 10.6*2.9 18.9*2,4 20.7+2.3 47.: a±6. 1. Including the standard error of the mean. w o ♦ TABLE XI •SUMMARY TABLE OF DIGESTIBILITY OF TWO CALCIUM SOAPS AND THEIR FATTY ACIDS Calcium Palmitate Palmitic Acid Calcium Stearate Stearic Acid and (m.p. 63°C) and (m.p. 69°C) Palmitic acid • Stearic aeid Data summarized Diet Diet Diet Diet Diet Diet E A B F A B Number of rats 5 5 5 5 5 5 Average gain, gm. -12 -1 0 -6 -3 0 Fat in diet, per cent 15 15 15 15 Calcium soap 10,00 10.47 Fatty acid 5.68 5,21 Total fatty acid 14.95 14.94 Average fat ingested, gm. 9,449 9.72 9,06 9.636 9.81 9.60 Average weight of stools, gm. 9,460 10,378 8.900 10.265. 11.802 9|84 Average fat excreted as: Neutral fat and fatty acid, gm, 1.077 3,886 4,894 1.303 3,993 6.919 "soap1 * , gm. 7.433 4.598 2.293 8,088 5.527 2.776 Average metabolie fat, gm. 0,615 0.674 1,317 0.667 0.765 1.545 Average fat excreted, (corrected), gm. 7.894 7,809 5^871 8,725 8.448 8.148 Coefficient of digestibility^- 16,7*4.0 19,8*3.4 35,6*1.9 9.0±Q.6 14,4*3.1 15.842,9 1. Including the standard error of the mean. p a (m.p. 56°C), tripalmitin (m.p. 66,5°C), and tristearin (m.p. ?0QC) show coefficients of digestibility of 37.7, 12.8, and 10.6 per cent respectively. Palmitic and stearic acids showed digestibilities of 19.8 and 14.4 per cent respectively. These latter two results agree well with those obtained on rats by Hoagland and Snider (25). When fat mixtures formed by the addition of 25 parts of palmitic or stearic acids to 75 parts of olive oil were fed, the digesti bility of the acids was found to be 23.8 and 19.8 per cent res pectively. The melting points of the two fats had been raised to 53°C for the palmitic acid mixture and 59°C for the stearic acid mixture. The explanation for the difference in digestibility between the mixed and simple triglycerides melting at a comparable tem perature may be due in some part to the fatty acid content,which is in agreement with results of the above authors (Hoagland and Snider). Thus a mixture of 10 parts of palmitic acid and 90 parts Of olive oil gave a melting point of 44°G, as did a mixture of 25 parts of myristic acid and 75 parts of olive oil, but in the former case the depression of digestibility was 6.6, while in the latter it was only 4.7. In individual fatty acid was found to raise the melting point and depress the coefficient of digestibility dependent to some extent upon its concentration in the mixture. Thus when the amount of stearic acid was increased from 10 to 25 per cent, raising the melting point from 43°C to 59°C, the depression of the coefficient 33. of digestibility was increased from 9*1 to 20.9. Calculation of the probable amount of stearic acid present in the mixtures of the lards with different melting points can be made from data in the literature on the fatty acid content of prime steam lard and from the degree of unsaturation as measured by the iodine number. Thus, the lards melting around 46°C were estimated to have a stearic acid content of approximately 18 per cent, while those melting at 55°C contained approximately 30 per cent stearic acid. The two coefficients of digestibility were 95 and 58 per cent respectively. Thus, along with the melting point increase, the amounts of less readily digested fatty acid components have some bearing. This is in agreement also with the work of Mattll and Higgins (36), When they fed mixed triglycerides to rats, mixtures of tristearin and triolein were more readily digested than tristearin itself, but not as readily as when the same proportions of these acids were incorporated in the glycerol molecule. Literature survey of the melting points of mixed glycerides and the practical experience of mixing fats of high and low melting points would make it seem certain that the mixture of triglycerides has a higher melting point than did the mixed triglyceride. However, the authors* explanation differs somewhat. They stated that mixed triglycerides are more readily digested than simple triglycerides, because the solvent action of oleic acid on stearic acid is greater in the 34. mixed glyceride than in the simple triglycerides. Therefore it would result in an increased rate of hydrolysis. This is also a possible explanation of the discrepancy observed in the case of bland lard, or mixed-fat-A, and trilaurin. Differences in iodine values may explain some of the dif ferences in digestibilities observed. The iodine numbers of the various fats, bland lardj mixed-fat-’ •A, hydrogenated lard (m.p. 55.4°C), and mixed-fat-B (m.p, 55.2°C) were 70,0, 76,0, 33,4, and 45,2, while their coefficients of digestibility were 92,4, 90,7, 58.0, and 66.2 per.cent respectively. Thus, in the two fats with a melting point close to 55°C, small differences in iodine number and thus in content of unsaturated fatty acids may explain the slight divergence in coefficient of digestibility. In the case of rapeseed oil, the long chain fatty acids are highly unsaturated. This may possibly explain its high degree of digestibility. In Table XII, a comparison is made between the saponification and iodine numbers of the rapeseed oils fed and the neutral fat and fatty acid extracted from the stools. <Tn both the crude and re fined oils, there was a decrease in saponification and iodine numbers. Thus it would appear that the fatty acids of shorter chain length and those of higher degree of unsaturation were selectively absorbed. Holt, Tidwell, Kirk, Cross, and Neals used in their experiments a partially hydrogenated corn oil (m.p. 50°C, iodine no, 50,2) and a 2:1 mixture of tripalmitin TABLE XII PHYSICAL CONSTANTS ON RAPESEED OILS Crude rapeseed oil Refined rapeseed oil Saponification number oil fed 166*8 167.7 fat excreted 106.7 123.1 Iodine number oil fed 101.1 96.3 fat excreted 60.5 v 67*5 36. and tristearin (m.p. 52°Gi iodine no. 2.4). The digestibility was 83 and 61 per cent. (30). These two fats have practically the same melting point, but differ widely in their content of unsaturated fatty acids. When the two extractions of excreted fat were compared, there was a marked difference between them. When low-melting fats such as bland lard and mixed-fat-A were used, the soap fraction was higher than the neutral fat-fatty acid fraction. The total amount of fat excreted was very low, and thus this increase did not appreciably alter the calculated values of the digestibility. However, in the tests on trilaurin, hydrogenated lard, mixed-fat-B and trimyristin, where the melting point was above 4?°C, the soap fraction greatly exceeded the neutral fat- fatty acid value in spite of the fact that the latter fraction was in most cases also considerably increased. In the case or the triglycerides such as tripalmitin and tristearin and the corresponding fatty acids, where the melting point was above 65°C, the neutral fat-fatty acid fraction was three to five times the soap fraction. Decreased digestibility was due to the increase in both the soap fraction and the neutral fat- fatty acid fraction. It is evident that in fats melting below 65°C, the soap formation was always higher than the neutral fat- fatty acid fraction, while if the melting point was above §5°c the reverse was true. The large portion of neutral fat-fatty 37. acid excreted after feeding tripalraitin and tristearin is ap parently due mainly to the fatty acid itself which was very in completely absorbed. It is excreted in the feces without alter ation. The calcium and magnesium content of the diet has a marked effect uppn digestibility of fat. The digestibility of natural fats such as bland lard and mixed fat of low melting point was found to be independent of this dietary salt level. However, the digestibility of synthetic triglycerides such as trilaurin, which has the same melting point as the bland lard and mixed-fat-A, was increased 25 per cent with the omission of the divalent ions from the diet. The calcium or magnesium soaps if formed from the bland lard and mixed-fat-A may be more soluble and thus better absorbed Is than those formed from trilaurin when calcium and magnesium salts are fed. The changes in digestibility of hydrogenated lard (m.p. 5 5 .4 °C ), mixed-fat-B (m.p. 5 5 .2 ° e ), hydrogenated lard (m.p. 61°G), trilaurin (m.p. 49°C ), and trimyristin (m.p. 56°C) were § 8 ,0 to 7 7 .9 , 6 6 .2 to 8 0 .0 , 1 7 .3 to 3 8 .0 , 7 0 .5 to 9 7 .3 , 37.7 to 7 6 .6 per cents respectively. This indicates that digestibility of fats increased 20 to 30 per cent in the diet when calcium and magnesium salts were absent. The extent to which absorption occurs may therefore depend not only upon the amount digested by the enzyme, but also upon the degree to which divalent ions are simultaneously present in the intestine to render the fatty acid insoluble and 38. nonutilizable. In the case of tripalmitin (m.p. 66.5°C), the digestibility differences between the diet with diyalent ions and without divalent ions was only 10 per cent. Tristearin di gestibility was unaffected by addition or withdrawal of divalent ions. Here there is probably little difference between the solu bility of the free acid and caleium and magnesium salts. The digestibility of stearic acid was found to be 14.4 and 15.8 per cent with and without calcium and magnesium, while that of palmitic acid changed from 19.8 to 35,6 per cent with the omission of the divalent ions. In all cases where calcium and magnesium are omitted from the diet, the excretion of soap is diminished and the digestibility of the fat increased in pro portion. In both acids, the soap fraction was higher in the calcium and magnesium diet, but the neutral fat-fatty acid fraction, although higher in the diet containing no ealeium and magnesium salts, did not compensate for a decrease in the soap fractions. Thus, a higher digestibility obtained in the animal fed no calcium or magnesium. This again indicated the -C0QH groups of fatty acids are available and immediately combine with divalent ions, to be excreted as salts; otherwise, the poorly absorbed fatty acids would be excreted unchanged. The digestibility of monostearin was 34 per cent with and 42 per cent without calcium and magnesium salts. Both these values are higher than the triglyceride (tristearin) and the fatty acid (stearic acid). If we accept the particulate 39. hypothesis, as put forward by Frazer (19) for fat ahsorption, the fat is finely emulsified in the upper part of the small intestine so that the particles average less than 0.5 in diameter and can be absorbed. This emulsified system does not increase the percentage of hydrolysis, but may allow un hydrolyzed fat to be removed from the intestine in particulate * ' form. Frazer (19) concluded that the emulsifying system which is effective only at a pH of 6.5 is the triple complex fatty- acid, bile, mono- or di-glyceride. A part of the monostearin may have entered into such a complex and thus have been ab sorbed. However, some of the fatty acid must have been split off, since the soap formation in the diets containing calcium and magnesium was relatively great. The effect of varying amounts of calcium and magnesium salts in the trilaurin diet was studied. When the salt level in the diet was reduced to 1/2 or 1/4 the normal level of calcium or magnesium, the soap fraction was also decreased. The average digestibility of the trilaurin was improved when the amount of these salts was decreased, but it did not reach the same level of digestibility as when fed without calcium and magnesium. This work further proves that calcium and magnesium are extremely effective in the diet for preventing the absorption of fat from the intestine. The results on feeding preformed calcium soaps indicate 40, an absorption similar to that obtained when the corresponding acids were fed in the presence of divalent ions. With both calcium palmitate and stearate, the amount excreted as soap is much higher than the amount-of soap fed. Some of the free fatty acids must have combined with other cations present in the digestive tract. There is no significant difference in digestibility between the preformed soap and soap which was formed in the intestine of the animals. In the ease of tripalmitin and tristearin, it is evident from Table XIII that a decreased hydrolysis also obtains, since most of the fat excreted in the feces was found in the form of triglyceride. It was found that only small amounts were present as the free acids. Acetyl values were determined to obtain information as to whether the esterified fats were totally in the triglyceride form. Calculated aeetyl values for di- and mono-palmitin are 92 and 270 respectively. Since the values obtained are mueh lower, it may be concluded that the largest percentage of this material was still in the triglyceride form. 41. TABLE XIII SUMMARY TABLE OF PHYSICAL CONSTANTS ON PAT EXCRETED AFTER FEEDING TRIGLYCERIDE Fat fed v : ' ' i - ' V - O Diet Ingested fat excreted as glyceride (calculated) per cent Fat break? Acetyl down number (calcul.) per cent Coefficient of diges tibility per cent Tripalmitin A 65,2 35,7 30.9 12.8 B 52,9 97.0 54.1 27.9 Tristearin A 68,3 31,6 38.0 10.8 B 69,7 30,3 32,1 18.9 CHAPTER V SUMMARY AND CONCLUSIONS 1, summary Digestibility of natural fats and synthetic triglycerides of various melting points has been studied* Fats having a melting point below 5Q°C were digested on an average of about 95 per cent, while those having melting points above 50°C showed a decreased utilization. The synthetic fat trilaurin, with a melting point of 49 °C, behaved in a man ner similar to that of the natural fats melting above 50°C, A study of the effect of divalent ions in the diet was made. The digestibility of partially hydrogenated lard (m.p. 5S,4°C) decreased from 77,9 to 58 per cent with the inclusion of calcium and magnesium salts. In the latter ease, a large proportion of the unabsorbed fat appeared as soap. The digestibility of synthetic triglyeerides melting at this level also decreased with the addition of divalent ions. Trilaurin (m.p. 49°C) averaged 70.5 per cent diges tibility without and 97,3 per cent with the addition of salt, but increased to 87,2 and 89.5 per cent digestibility when the diet contained 1/2 and 1/4 the original amount of salts. The corresponding changes in the digestibility of trimyristin (m.p. 56°C), tripalmitin (m.pm 6615°C), and tristearin (m.p. 70°c) were 37,7 to 76.6 per cent, 12.8 to 27.9 per cent, and 10.6 to 18.9 per cent with and without divalent ion salts respectively. In the ease of crude and refined rapeseed oils, the digesti bility was 92 per cent with and 93 per cent without the di valent ions ih the diet. In the test with monostearin (m.p. 59.9°C), the digestif bility was 20.7 per cent with and 47.3 per cent without adding divalent calcium and magnesium salts. The digestibility of calcium stearate was 9.0 per cent, and that of calcium palmitate was 16,7 per cent. The digestibility of palmitic (m.p, 63°C) and stearic acids (m.p. 69Q| J ) increased from 19.8 to 30.6 and from 14,4 to 15.8 per cents respectively when calcium and magnesium salts were withheld from the diet. 2* Conclusions 44, An attempt to correlate the melting point of fats with coefficient of digestibility demonstrates that, in general, sueh a correlation exists. However, other factors also have an influence. Simple glycerides show a decrease in digesti bility at a lower temperature than do mixed glycerides. Fats containing large amounts of unsaturated fatty acids of long chain length are readily absorbed. The acid radical and the degree of unsaturation appear to be factors affecting the coefficient of digestibility. The incorporation of considerable amounts of calcium and magnesium into the diet was found to decrease the digesti bility of natural and synthetic fats with melting points above the critical 50°C. The magnitude of the decrease was dependent upon the fat, with a maximal effect when the melting point of the fat was between 5G°C and 65°C. Above 65°C, where digestibility is low, little effect could be noted. Apparently there is little difference between the solubility of the fatty acid and its respective calcium salt. Preformed calcium palmi tate and stearate were digested to the same extent as when those salts were formed in the intestinal tract as a result of large amounts of calcium in the diet. BIBLIGGBAHiy 46. 19, Frazer, A. C. J. Physiol. 26:103, 1946. 20. Givens, M. J. Biol. Chem. 51:441, 1917. 21. Gogildse, S. Zelt. f. Biol. 46;403, 1904-1905; 22. Greengard, H., M, Jt Grossman, J, R. Wopley, and A. C, Ivy. Science 99:350, 1944. 23. Harper, A. A., and H, S. Raper. J. Physiol. 102:115, 1943. 24. Hoagland, R. and G. G. Snider, J. Nutrition 25:295, 1942. 25. Hoagland, R. and G, G. snider. J. . Nutrition 26:219, 1943. 26. Holmes, A. D. S. Dcp t. Agr. Hull, Ho, 630, 191©. 27. Holmes, A. D. U. S. Dept. Agr. Bull. Ho. 613, 1919. 28. Holmes, A. D, U. S. Dept. Agr. Bull. Ho. 781, 1919. 29. Holmes, A. D., and H. J. Deuel, Jr. Am. J. Physiol. 54:479, 1921; 30. Holt, E., Jr., H. C. Tidwell, C. M. Kirk, D, M. Cross, and S. N. Heale. J. Ped. 6:427, 1935. 31. Jansen, C, P, Z^ physiol. Chem. 72:158, 1911. 32. Kalaboukoff, L. and Terroine, E. F. Compt. rend. Soc. Biol. 63:372 taken from Bloor, 1943. 33. Langworthy, C. F, J, Ind. Eng. Chem. 15:276, 1925. 34. Langworthy, C, F., and A. D. Holmes. S^ Dept. Agr. Bull. NO. 310, p. 505. 1915, 35. Langworthy, C. F., and A, D. Holmes. Sj_ Dept. Agr. Bull. Ho. 507. 1917. 36. Levites, S. Z. physiol.Chem. 53:349, 1907. Mattil, K. F.,and J. W. Higgins. J. Nutrition 29:255, 1946. 37. Lyman, J. F, J. Biol. Chem. 52:7, 1917. Mellanby, J. J. Physiol. 60:85, 1925. 47* 38* MeCay, G* M. and H. Paul J. nutrition 15:377, 1938. 39. McClure, C. W., B. Vincent, and J. H. Pratt. J. Exp. Med. 25:381, 1917. 40. Osborne, T, and L, B. Mendel. ' Biol Chem. 37:572, 1919. 41. Paul, H. and C. M* MeSay. Arch. Biochem. 1:247, 1942. 42. Pratt, J, H., P. D. Lamson, and H, K. Marks. Trl. Ass, Am. Physicians 24:266, 1909. ” 43. Bapp, K. E., J; I, Skinner, and J. S. MeHargue. J. Nutrition 31:273, 1946. ' 44. Rockwood, E. W., and P. B, Siviekes. ^ A^ 71:1649, 1918* 45. Rothberg, 0. Jahrb. Kinderheild. 66:69, 1907. 46. Sandmeyer, W. Zelt. f. Biol. 13:12, 1894, 47. Sehiff Arch, Physiol Norm. Path.4:699, 1892. Taken from Bloor, 1943.r 48. Smith, C, A,, R, J, Miller, and P. B. Hawk. J. Biol. Chem, 23:505, 1915. 49. Verzar, P. and E, J* McDougall. Absorption from the Intestine. Longmans, Green and Co., New York. 1936. 50. West, E. S., C. L. Hoagland, and G. H. Curtis. J. Biol. Chem. 104:627, 1934. 51. Willstatter, R. E,-, E, Waldschmidt-Leitz, and F. Memmen. Z. physiol. Chem. 135:93, 1928. 52. Woodman. Food Analysis. McGraw, Hill Book Company, New York 1941. JiPFEBDIX TABLE XIV THE DIGESTIBILITY OF BLAND LARB (M.P. 47.8°C) BY FEMALE BATS Length Body weight Weight Extracted Extracted fecal Coefficient Rat of Ingested of fat from feces fat (corrected) of no. exp’t Start End Food Fat dried feces Neutral fat, Soap Total Metabolic Total Digestibility days gm, gm. gnu gm. gm. fatty acids gm. gm. gm. gm. per cent gm. Diet A - contains calcium and magnesium salts 601 8 168 169 77 11.55 4,248 0,162 0,617 0,779 0.276 0.503 95,6 602 8 165 172 94 14,10 5.934 0,263 1,257 1,500 0.386 1,114 92.0 603 8 164 166 78 11,70 4,997 0,212 0,872 1.084 0,325 1,759 93.5 604 8 157 159 96 14,40 6,949 0,371 1,260 1,631 0.452 1.179 91.8 605 8 179 178 98 14,70 6,571 0,225 1.790 2* 015 0,427 1,588 89,2 Average 166,6 168,8 0 0 0 0 . j 13. 29 5.739 0.247 1,155 1,401 0.353 1,028 92.4 A 0,94 Diet B « * contains no calcium or magnesium salts 606 8 178 183 91 13.65 3.429 0.494 0.883 1.377 0,507 0,870 93.6 607 8 174 174 79 11.85 2.659 0.359 0,704 1*063 0.394 0,669 94.3 608 8 164 166 77 11.35 1.943 0.323 0,332 0,655 0.288 0.367 96.8 609 8 163 167 94 14.10 3.449 0.397 0.398 0,795 0.510 0,285 97.9 600 8 164 165 66 9,90 3,160 0,397 0,404 0,801 0.468 0,333 96.6 Average 168.6 171 81.4 12.21 2.728 Q.394 0.544 0.934 0.433 0,505 95.8 + 0.60 TABLE XV THE DIGESTIBILITY OF MIXED-FAT-A (M.P. 47.9°C) BY FEMALE RATS Length Body Rat of weight Ingested Weight Fat extracted of from feees Extracted fecal Coefficient fat (corrected) of no. exprt Start End days gm. gm. Food Fat gm. gm. dried feces Neutral fat, Soap gm. fatty acids gm, gm. Total Metabolic Total Digestibility gm, gm. gm. per cent Diet A - contains calcium and magnesium salts 706 8 184 188 91 13,65 6,632 0.279 1.522 1,801 0.431 1,370 89.9 707 8 169 168 74 11,10 4.927 0.155 1.018 1.173 0.320 0,853 92.3 708 8 186 188 97 14.55 6.961 0. 216 1.683 1.899 0.452 1.447 90.0 709 8 181 187 99 18,85 6.681 0,289 1.260 1,549 0.434 1.115 94.1 800 8 178 182 82 12.30 5.805 0,271 1,663 1.934 0,377 1,557 87.3 Average 179.6 182.6 88.6 14,09 6.201 0.242 1,429 1,671 0.402 1,268 90.7+2.2 Diet B - contains no calcium or magnesium salts 801 8 170 167 79 11.85 1.764 0.270 0*434 0.704 0.261 0.443 96.2 80S 8 155 •162 73 10,95 1.774 0.265 0,393 0.658 0,263 0,395 96.3 803 8 171 173 117 17,55 3.648 0.529 0.818 1,347 0.540 0,807 95.4 804 8 157 154 76 11.40 1,708 0.322 0,438 0.760 0.253 0,507 95.5 805 8 180 186 112 16.80 2.983 0.493 0.797 1,290 0.441 0,849 94.9 Average 166.6 168.4 91.4 12.51 2,375T 0.376 0.572 0.952 0.352 0.608 95.6±0,51 TABLE XVI THE DIGESTIBILITY OF HYDROGENATED LABD (M,P. 55,4°C) BY FEMALE RATS Length Body Rat of weight' Ingested Weight of Fat extracted from feces Extracted fecal Coefficient fat (corrected) of no. exp't start End days gm. gm. Food Fat gm. gm. dried feces Neutral fat, Soap gm, fatty acids gm. gm. Total Metaboiic Total Digestibility gm. gm. gm. pdr cent Diet A ” contains calcinm and magnesium salts 100 8 183 183 73 10*95 8.413 0,784 4,735 5.519 0.547 4.972 54,5 101 8 201 198 81 12,10 9.092 0.398 5.565 5.963 0,591 5.372 55.6 102 8 180 180 65 9.75 5.300 0.439 2,238 3.377 0.345 3,032 68.9 103 8 162 165 74 11,10 8.505 0.378 4,937 5,315 0.553 4.762 57.0 104 8 159 159 75 11.25 8,68? 0.570 5.156 5.726 0.565 5.161 54.1 Average 177 177 73.6 11,777 7,999 0*514 4,666 5,180 0.520 4.659 58.0±2.4 Diet B - contains no calcium or magnesium salts 105 8 187 187 72 10.80 4,003 1.234 1,494 2,728 0.592 2«l36 80.2 106 8 162 157 60 9.00 4.547 1,621 1.163 3,784 0. 673 2.111 76,5 107 8 187 179 61 9.15 4.495 1.492 1,707 3.199 0.665 2,534 72,3 108 8 162 163 59 8,85 2.967 0.813 1,319 2.132 0.439 1,693 80,8 109 8 164 160 53 7.96 2.954 0,709 1.324 2,033 0,437 1,596 79,9 Average 172.4 169.2 61 9.15 3.798 1.174 1.401 2.575 0.561 2.014 77.9 +0.48 TABLE XVII THE DIGESTIBILITY OF MIXED“FAT”B (M.P. 55.2°C) BY FEMALE RATS Length Body T Rat of weight Ingested Weight of Fat extracted from feces Extracted fecal fat (corrected) Coefficient of no. exp't Stiart End days gm. gm. Food ’ Fat gm. gm. dried feces Neutral fat, Soap gm. fatty acids gm. gm. Total Metabolic Total gm. gm. gm. Digestibility per cent Diet A “ contains calcium and magnesium salts 501 8 172 173 73 10.95 7.107 0,569 4,0764.c4.645 0,462 4.183 61,7 502 8 175 177 89 13.35 8,201 1.566 3,064 4.630 0.533 4.097 69.3 503 8 190 185 55 8.25 5.455 0.924 2.514 3,438 0,355 3,083 62,6 504 8 171 173 66 9.90 7.112 0,934 3.047 3.981 0.462 3.519 64.4 505 8 177 172 73 10.95 7,064 1,283 2,150 3.433 0,459 2,974 72.8 Average Diet 177 B - i 176 contains 71.2 10,68 no calcium or 6,988 magnesium 1,055 salts 2,972 4.028 0.454 3.573 66.2±1.8 506 8 167 168 61 9.15 4,115 1.524 1.436 2,960 0.609 2.351 74,3 507 8 159 155 46 6.90 2.900 1.085 0,907 1.992 0J.429 1.563 77,3 508 8 175 175 79 11,85 4.729 1,728 1.456 3.184 0.700 1.484 79.0 509 8 175 173 53 7,95 2.845 0,987 0,946 1.933 0,421 1.512 80.9 600 8 166 166 63 9.45 3,390 1.314 1.042 2.356 0.502 1,854 80.3 Average 168.4 167.4 60.4 9.06 3.596 1.328 1.157 2.285 0.532 1.753 80,0+1.9 TABLE XVIII THE DIGESTIBILITY OF HYDROGENATED LARD (M*P» 61°C) BY FEMALE RATS Length Body Rat of weight Ingested Weight Fat extracted of from feces Extracted fecal fat {corrected) Coefficient of no. exp’t Start End days gm. gm. Food Fat dried feces Neutral fat, Soap gm. fatty acids gm. gm. Total Metabolic Total gm, gm. gm. Digestibility gm. Diet A - contains calcium and magnesium salts 302 8 183 179 73 10.95 12.503 3.696 6,575 10.271 0.812 9.459 13.6 303 8 169 166 84 12.60 13.522 5.118 5.853 10.971 0.879 10*092 19.9 304 8 172 165 66 9.90 11.889 3.373 6.568 9.941 0.773 9.168 7.3 303 8 173 166 69 10.35 10,297 2.926 5.141 8,067 0.669 7.398 28.5 Average 174.2 169 Diet B ~ contains 73 10.95 no calcium or 12.052 3.778 magnesium salts 6.034 9.812 0.783 9.029 1?.3±3.0 306 8 180 172 70 10.50 10661 7.183 1.894 9.077 1.578 7.499 28.5 307 8 168 169 71 10.65 12.644 6.489 2.889 9.378 1.871 7.507 29.5 308 8 165 166 69 10.35 9.164 6.070 1.967 8.037 1,356 6.681 f0.4 309 8 168 163 60 9.00 7.579 4.450 1,767 6. 217 1.122 5. 095 §3.3 400 8 165 174 82 12.30 9.532 5.691 1.454 7.145 1.411 5.734 53.5 Average 169.2 168.8 70.4 10.56 9.916 5.977 1,994 7.971 1,467 6.503 38.0 ±3. 6 TABLE XIX THE DIGESTIBILITY OF CRUDE AND REFINED RAPESEED OIL BY sEMALE RATS FED WITHOUT CALCIUM OR MAGNESIUM SALTS Lengtn Body Weight Fat extracted Extracted fecal Coefficient Rat of weight Ingested of from feces fat (corrected) of no. ezp'f; Start End Food Fat dried feces Neutral fat, Soap Total Metabolic Total Digestibility days gm. gm. gm. gm. gm. Fatty acids gm, gm, gm. gm. per cent gm. .» > Diet B - crude rapeseed oil, nc) calcium or magnesium salts 1031 8 181 180 71 104 65 1.738 0.689 0,736 1.425 0,257 1,168 89.0 1032 8 190 188 77 11.55 1.716 0.384 0,350 0.734 0.254 0.480 95.8 1033 8 180 175 75 11.25 2.208 0.822 0.691 1.513 0,327 1.186 89,4 1034 8 164 155 63 9.45 2.289 0.934 0.282 1.216 0.339 0.877 90.7 1035 8 160 156 61 9.15 4.531 0,453 0.493 0.946 0. 671 0.275 96.9 Average Diet 175 170.8 69.4 10.41 B - refined rapeseed oil, 2.496 0.656 0.510 no calcium or magnesium salts 1.167 0,370 0.797 92,3±1.4 1036 8 163 166 65 9.75 1.671 0.502 0.264 0.766 0.247 0.519 94.6 1037 8 173 175 80 12.00 2.517 0.823 0.465 1.288 0.373 0,915 92.3 1038 8 151 155 73 10.95 1,789 0,502 0.244 0.746 0.265 0.481 95.6 1039 8 166 165 67 10,05 1.707 0,433 0.332 0,765 0,253 0.512 94.9 1040 8 170 169 75 11.25 1.974 0.601 0.564 1.165 0.292 0.873 92,2 Average 164.6 166 72 10.80 1.932 0.572 0.394 0.946 0.286 0.660 93.9ii.62 TABLE XX THE DIGESTIBILITY OF TRILAURIN (M.P. 49°C) BY FEMALE RATS Length Rat of Body weight Ingested Weight of Fat extracted from feces Extracted fecal fat (corrected) Coefficient of no. expft Start End days gm. gm. Food gm. Fat gm. dried feces gm. Neutral fat, fatty acids gm. Soap gm. Total Metabolic gm. gm. Total gm. Digestibility per cent Diet A - contains calcium and magnesium salts 71B 8 72B 8 73B 8 71 8 72 8 73 8 208 201 186 175 175 168 147 145 142 142 160 155 66 57 59 59 63 50 9.90 8.55 8.85 8.85 9.45 7,50 5.966 5.777 5.132 4,139 4. 566 3.233 0.219 0.252 0.181 ‘ 0.203 0,241 0.162 3.577 3.123 2.777 2.121 2.740 1,966 3.796 0.387 3.374 0.326 2,958 0.334 2,324 0,273 2.981 0,297 2.128 0.210 3.409 2,998 2.624 2,055 2,684 1,918 65.2 64.9 70.3 76.7 71.5 74.4 Average a . 169.6 165.8 59 8.85 4,802 0.251 2,717 2.928 0,312 2.614 70.5 + 1.7 Diet B - contains no calcium or magnesium salts 76 8 166 169 51 7.60 1,505 0,153 0,367 0.520 0.223 0,297 96.0 77 8 166 170 72 10.80 3,115 0.263 0.368 0.631 0.461 0.170 98.4 78 8 175 167 40 6.00 01655 0.091 0.175 0.266 0.097 0,169 97.1 79 8 158 162 67 10.05 1.686 0,211 0.325 0.536 0.250 0.286 97.1 80 8 176 175 62 9.30 0.811 0.083 0,223 0.306 0.120 0.186 98,0 Average 168.2 168,6 58.4 8.75 1.554 0J60 0.292 0.452 0.330 0.222 97.3 TABLE XXI THE DIGESTIBILITY OF TRILAURIN (M.B.49°C) BY FEMALE BATS FED VARYING AMOUNTS OF CALCIUM AND MAGNESIUM Length Body Weight Fat extracted Extracted fecal Coefficient Rat of weight- Ingested of from feces fat (corrected) of no, exp’t Start End Food Fat dried feeds Neutral fat, Soap Total Metabolic Total Digestibility days gm. gm. gm. gm. gm. fatty acids gm. gm. ©n. gm. per cent gm. Diet C • Same salts as Diet No. 1, except that Ca and Mg salts were reduced to l/2. 1046 7 149 159 51 7,65 2.951 0.184 1.126 1,310 0,192 1.118 85. 3 1047 7 157 167 53 7.95 1.730 0.241 0.790 1.031 0.113 0.918 88,4 1048 7 165 163 39 5,85 1.669 0.119 1,005 1.124 0,108 1.016 82.6 1049 7 168 178 54 8.10 1.598 0,205 0.791 0.996 0,104 0,892 88.9 1050 7 164 174 55 8,25 1.942 0.377 0.520 0.897 0.126 0.771 90,6 Average 160.6 168.2 50.4 7,56 1.978 0,225 0.846 1,072 0.129 0,943 • 87,2± 4.0 Diet D - Same salts as Diet No. 1, except that Ca and Mg salts were reduced to 1/4. 1051 8 181 167 48 7.20 1.793 0.272 0.566 0.838 0.117 0,721 89,9 1052 8 170 168 57 8.55 2.226 0,177 0.913 1.090 0.145 Q.945 89,9 1053 8 183 184 9? 14.40 3.091 0.673 0,666 339 0.201 1.138 92,0 1054 8 175 171 68 10,20 2.322 0.287 0,802 1.089 0,151 0.938 90.8 1055 8 153 147 63 9,45 2.925 0.504 0.996 1.500 0,190 1,310 86,1 Average 172.4 167.4 6b.6 9.96 2.471 0,383 0.789 H I , 171 0.161 1.010 89.5±,85 CD c r . TABLE XXII THE DIGESTIBILITY OF TRIMYRISTIN (M.P. 56°C) BY FEMALE RATS Length Body Rat of weight Ingested Weight Fat extracted of from feces Extracted fecal fat {corrected) Coefficient of no e*pft Start End days gm, gm. Food Fed* gm. gm. dried feces Neutral fat, Soap gm. fatty acids gm. gm. Total Metabolic Total gm. gm. gm. Digestibility gm. Diet A - contains calcium and magnesium salts . 5 1 8 175 178 68 10.20 8. 544 0,887 6,155 7.042 0,555 6.487 36.4 52 8 177 182 92 13,80 11.072 1.014 8,402 9,416 0,720 8.696 36. 9 53 8 186 186 94 14.10 10.797 1.297 7.735 9,032 0,702 8,330 40.9 54 8 190 183 77 11.55 10.595 1.141 7.339 8.480 0,689 7,791 32.5 55 8 188 193 94 14.10 11.619 1,249 7,685 8,934 0,755 8,179 41,9 Average 183.2 188.4 85 . . . . . 12,75 10,525 1.118 7,463 8.582 0.684 7,897 37,7± 1,4 Diet B - contains no calcium or magnesium salts S L IB 8 167 167 61 9.15 3.441 1.147 1,385 2,532 0,509 2.023 77,8 72B 8 159 159 64 9,60 3.502 1,481 1.033 2.514 0.518 1,996 79.2 73B 8 167 171 60 9.00 3.978 1.722 0.933 2, 655 0.589 2.066 77.0 74B 8 186 190 77 11, 55 4,646 1.895 1,634 3,529 0.688 2.841 75.4 75B 8 164 165 61 9 .15 3.570 1.229 1.671 2.900 0.528 2.372 74.0 Average 168.6 170.4 64.6 9*69 4.433, 1.494 1.331 2,826 0.563 2.259 76.6 + 0.81 TABLE m u THE DIGESTIBILITY OF PALMITIC ACID (M.P. 63°G} BY FEMALE RATS Length Body Weight Fat extracted Extracted fecal Coefficient Rat of weight Ingested of from feces fat (corrected) of no. exp*t Start End Food Fat dried feces Neutral fat, Soap Total Metabolic Total Digestibility days gm. gm. gm. gm. gm. fatty acids gm. gm. gm. gm. per cent gm. Diet A “ contains calcium and magnesium salts 31 8 148 158 68 10,20 9.794 4.190 4.384 8,574 0,637 7.937 22*1 32 8 155 150 67 10.05 10,515 4,048 5,761 9,809 0,683 9.126 9.1 33 8 161 170 83 12.45 13,547 5,984 4.104 10,088 0.881 9.207 26.0 34 8 172 171 62 9,30 10,653 3.417 5.396 8.813 0,692 8.121 12.6 35 8 166 159 44 6,60 7,381 1,791 3.344 5,135 0.480 9,655 29.5 Average 160.4 161.6 64.8 9,72 10,378 3,886 4,598 8,484 0.674 7,809 19.8±3.4 Diet B “ contains no calcium or magnesium salts $6 8 170 169 59 8.85 8,811 3,773 3.105 6.878 1,304 5,574 37.0 37 8 158 151 55 8.25 81468 5,358 1.864 7.222 1.253 5.959 27.6 38 8 156 156 55 8,25 8,160 4,304 2,141 6,445 1.208 5.246 36.4 39 8 159 158 55 8.25 8,087 4,170 1,895 6.065 1.197 4.868 40.9 40 8 165 170 78 11,70 10,972 6.865 2,458 9,323 1,624 7,699 34.2 Average 161.6 160.;8 60.4 9.06 8.900 4,984 2,293 6,966 1.317 5.871 35.6 + 1,9 § ♦ TABLE XXIY THE DIGESTIBILITY OF STEARIC ACID (M.P. 69°C) BY FEMALE RATS Length Body Weight Fat extracted Extracted fecal Coefficient Rat of weight Ingested of from feces fat (corrected) of no. exp*t Start End Food Fat dried feees Neutral fat, Soap Total Metabolic Total Digestibility days gc a . gm. gm. gm. gm. fatty acids, gm. gm. gm. gm. per cent gm. Diet A “ contains calcium and magnesium salts 41 8 161 156 67 10,05 11.371 2.573 6.164 8.737 0.739 7,998 20,4 42 8 157 153 54 8.10 9.733 3,850 3,414 7.264 0.633 6.631 18,1 43 8 175 173 62 9.30 11,427 4.290 3.754 8.044 0.743 7,301 21.4 44 8 169 160 64 9.60 11.394 3.713 5,861 9,574 0,752 8.822 7.9 45 8 165 170 80 12.00 15.087 5.539 6.925 12.464 0.981 11.483 4.3 Average 165..4 162.4 65.4 9.81 lli802 3.993 5.527 9.217 0,765 8.448 14.4±3.1 Diet: B - contains no calcium or magnesium salts 46 8 154 162 82 12,30 13.807 10.348 2.298 12.646 2.043 10.603 13,7 47 8 148 148 70 10,50 11.646 8.173 2.893 11.066 1.724 9.342 11,0 48 8 162 154 48 7.20 7.121 3.913 2.370 6,283 1,034 5,229 27.3 49 8 158 158 61 9.15 9,428 6.767 2,982 9.749 1,395 8,354 8,7 50 8 169 168 59 8.85 10.200 5.392 3.335 8,727 1.510 7,217 18.4 Average 158,2 158 64 §760 9,840 6.919 2,776 9,694 17545 8,148 15.8±2,9 TABLE XXV THE DIGESTIBILITY OF MONOSTEARIN (M,P, 59,9°C) BY FEMALE RATS Length Body Rat of weight Ingested Weight Fat extracted of from feces Extracted fecal rat (corrected) Coefficient of no. exp’t Start End days gm. gm. Food gm. Fat dried feces Neutral fat, Soap gm. fatty acids, gm. gm. Total Metabolic Total gnu gm. gm. Digestibility per cent Diet A - contains caleium and magnesium salts 61b 8 160 152 73 10.95 12,476 3,368 6.111 9.978 0,811 9,167 16.3 62b 8 153 143 63 9,45 10.227 3,288 4,048 7,336 0.665 6.671 29.4 63b 8 157 148 . 65 9,75 10,388 3,193 5,335 8,528 0.675 7,852 19.4 64b 8 160 151 70 10,50 11,992 3,176 5.624 8,800 0,779 8,051 23,6 65b 8 162 150 67 10,05 10,329 2,577 6,640 9.217 0,671 8,536 15.0 Average 158,4 148,4 67,6 10.14 12,096 3, 220 5,552 8.772 0,720 8.062 20.7*2.3 Diet B • contains , no calcium or magnesium salts 66b 8 143 138 62 9,30 6.827 1.497 1.833 3.330 1.010 2,320 75.0 67b 8 149 139 57 8.55 7.391 3, 666 1,888 5.554 1,094 4.460 47,8 68b 8 146 145 76 11.40 7,439 4.032 1.907 5.939 1,101 4,838 57,1 69b 8 15Q 145 69 10.35 9.182 7,163 1,859 9.022 1.359 7.663 25.9 70b 8 139 132 52 7.80 5.999 3.650 1.717 5.367 0.888 4,479 42.5 Average 145.4 139.8 65.2 9,48 7,368 4.008 1.840 5.842 1.090 4.752 4?.4±,6.7 O’ - o * TABLE XXVI THE DIGESTIBILITY OF TRIPAIMITIN (M.P. 66.5°C) BY MALE BATS Length Body Bat of weight Ingested Weight Fat extracted of from feces Extracted fecal fat (corrected) Coefficient of no. exp’t Start End days gm. gm. Food Fat gm. gm. dried feces Neutral fat, Soap gm. fatty acids, gm. gm. Total letaholie Total ©a. gm. gm. Digestibility per cent Diet A - contains calcium and magnesium salts 11 6 165 162 54 8.10 9.983 5.649 2.137 7.786 0.649 7.137 11.9 12 6 161 150 59 8,85 12.067 6.724 2.096 8.820 0.784 8.036 9.1 IS 6 173 175 63 9.45 11.843 6.937 1.830 8.767 0.770 7.997 15.3 14 6 187 188 58 8.70 11.445 6.070 1.919 7.989 0.744 7.245 16.9 15 6 181 182 69 10.35 13.016 6.633 34390 10.023 0.846 9.177 11.3 Average Diet 173,4 171,4 60.3 9.09 B - contains ng calcium or 11.670 6,400 magnesium salts 2,274 8.677 0.759 7,918 12,8*1.2' 16 6 176 167 73 10.95 10.988 7.294 1.512 8.806 1.626 7.180 34,4 17 6 165 169 63 9.45 10.568 7.163 1,452 8,615 1.564 7.051 25.3 18 6 169 168 68 10.20 12.164 8,905 1.195 9.100 1.800 7.300 28.4 19 6 155 156 62 9.30 9.986 7.273 1.291 8.564 1.478 7.087 23,8 20 6 150 152 61 9.15 8.155 6.934 0.906 7,840 1,207 6.633 27,5 Average 163 162.4 65.4 9,81 10.394 7,514 1.271 8.585 1.538 7,248 27,9 ±1.5 TABLE XXVII THE DIGESTIBILITY OF TRISTEARIN (M.P. 70°C) BY FEMALE RATS Length Rat of Body weight Ingested Weight Fat extracted of from feces Extracted fecal fat (corrected) Coefficient of no. exp’t days Start End gm. gm. Food Fat gm. gm. dried feces Neutral fat, Soap gm. fatty acids, gml gm. Total Metabolic Total gm. gm. gm. Digestibility per cent Diet A - contains calcium and magnesium salts 21 6 176 174 70 10.50 14.089 8.642 2.117 10.759 0,916 9.843 6,2 22 6 158 154 73 10.95 14.749 9.282 2.243 11.525 0.959 10.569 3.4 23 6 161 161 60 9.00 11.595 7.060 1.755 8.815 0.754 8.061 10.4 24 6 159 159 48 7.20 7.924 5.047 1.048 6,095 0.515 5,580 22^5 25 6 150 155 67 10.05 12,189 7.481 2.310 9.791 0.792 8.989 10.5 Average 160.8 160,8 63,6 9.54 12,108 7,502 1.896 9.397 0.789 8.607 10.6+ 2.9 Diet B - contains no calcium or magnesium salts 86 6 174 174 59 8.85 9.333 6.978 0.810 7,788 1.381 6.407 27,6 27 6 179 173 59 8.85 10,418 7.820 0.911 8.731 1.542 7,189 18.7 28 6 171 172 66 9.90 11.297 8.705 0,679 9.384 1.672 7,712 22.1 29 6 153 148 59 8.85 11.432 8.419 1.011 9.430 1.692 7.738 12.5 30 6 169 167 57 8.55 10.400 7.924 0.991 8.915 1.539 7.376 13.7 Average 169.2 166.8 60 9.00 10.556 7,969 0.880 8,849 1.545 7.284 18.9± 2.4 o> 63, TABLE XXVIII PHYSICAL CONSTANTS ON FAT EXCRETED . IN THE STOOLS AFTER FEEDING TRISTEARIN Rat Titration Ingested fat Coefficient no. Diet of fatty . excreted as Fat Acetyl of acids triglycerides breakdown number Digestibility (cq. 0.1N NaOH/gnufat) gm, per cent per cent 21 A 5*3 0,849 69.8 3Q.2 34,3 6.2 22 4,1 0.884 74.8 25.2 30*2 3.4 23 7.5 0.787 61.7 38.3 43.6 10,4 24 2,3 0,935 65.5 34,5 44.2 22.5 25 2.2 0.938 69.8 30.2 37.9 10,5 Average 4.2 0,878 68*3 31.6 38,0 10. 6 ±2.9 26 B 8.48 0.759 59.8 40.2 29.2 27.6 27 3.53 0.900 79.5 20.5 37i 0 18.7 28 5.83 0,834 73^3 26; 7 42.6 2211 29 5.72 0.724 68.8 3i;2 29,0 12.5 30 - 9.76 0.723 66.9 33.1 23.0 13.7 Average 6,66 0,790 69,7 30,3 32,1 18.9±2.4 TABLE XXIX PHYSICAL CONSTANTS ON FAT EXCRETED IN THE STOOLS AFTER FEEDING TRIPALMITIN Titration Ingested fat Coefficient Rat of fatty excreted as Fat Acetyl of no. Diet acids triglycerides breakdown number Digestibility (cc. 0.1N (calc) NaOH/gm. fat) gm. per cent per cent ■ ^ 5 * 11 A 3*67 0.906 63.1 36.9 18.7 U.9 12 1.81 0,954 72.4 27,6 35.9 9.1 13 1.11 0.972 71.3 28.7 37,3 15.3 14 2,66 0;.932 65.0 35.0 20.8 16.9 15 5,91 0.849 54.3 45.7 42.2 11.3 Average 3.03 0,922 65.2 35,7 30,9 12.8 ±1.2 16 B 8.91 0,772 51.3 48,7 65.6 34.4 17 13.1 0,665 50,3 49.7 58,2 25.3 18 12,1 0,690 60.2 39.8 70.3 28.4 19 15,1 0.613 47.9 52.1 29.0 23.8 20 10.7 0,276 54.9 45.1 47.6 27*5 Average 11.9 0.693 52.9 ' 47.0 54,1 27,9±1,5 TABLE XXX THE DIGESTIBILITY OF CALCIUM PAIMITATE BY FEMALE BATS Length Body Weight Fat extracted Extracted fecal Coefficient Rat of weight Ingested of from feces fat (corrected) of no. exp*t, Start End Food Fat dried feces Neutral fat, Soap Total Metabolic Total Digestibility days gm, gm. gm. gm. gm. fatty acids, gm, gm. gm, gm. per cent 1041 8 174 158 56 8,372 9,141 0,810 7,807 8,617 0,594 8,023 4,1 1042 8 175 166 76 11.362 12,488 1.514 9.927 11.441 0.812 10,629 6.4 1043 8 170 155 58 8,671 7.859 0,910 6.105 7,015 0.511 6,497 24.9 1044 8 168 157 63 9.419 8.259 0,863 6,020 6,883 0.539 6,346 32.6 1045 8 174 161 63 9.419 9,554 1.289 7,308 8,597 0,621 7.976 15. 7: Average 172.2 159.4 63,2 9.449 9.460 1,077 7,433 8.510 0*615 7,894 16,7± 4,0 University o f Southern California Library TABLE XXXI THE DIGESTIBILITY OF CALCIUM STEARATE BY FEMALE RATS Length Body Weight Fat extracted Extracted fecal Coefficient Rat of weight Ingested of from feces fat (corrected) of no* expM; Start End Food Fat dried feces Neutral fat, Soap Total Metabolic Total Digestibility days gm. gm. gm. gm. gm. fatty acids gm. gm. gm, gm. per cent gm. 82b 7 171 164 64 9*562 16,284 1.265 8.397 9.662 0*668 8.994 ' 5.9 83b 7 177 167 73 11.205 11.878 1.460 8.796 10.256 0,772 9.484 15.3 84b 7 185 178 43 6.424 6.419 0.775 5^648 6.423 0.417 6i006 6.4 85b 7 ISO 160 76 11.354 12.480 1.715 9.512 11.227 0.811 10.416 8.2 Average 173*2 167,2 64*5 9.636 10,265 1.303 8t088 9,392 0,667 8,725 9,0 + 0.60 c r » & >

Asset Metadata

Creator Cheng, Amber Lieng-shan (author)

Core Title Studies on fat digestibility: The effect of melting point and dietary calcium and magnesium level

Contributor Digitized by ProQuest (provenance)

Degree Doctor of Philosophy

Degree Program Biochemistry

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag health sciences, nutrition,OAI-PMH Harvest

Language English

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c17-606056

Unique identifier UC11354903

Identifier DP21537.pdf (filename),usctheses-c17-606056 (legacy record id)

Legacy Identifier DP21537.pdf

Dmrecord 606056

Document Type Dissertation

Rights Cheng, Amber Lieng-shan

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

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